The basic operation and structure of land mobile radio communication systems are known. Communication systems typically comprise a plurality of communication units (vehicle mounted or portable radios in a land mobile system and radio/telephones in a cellular system), a predetermined number of base stations, which are located throughout a geographic region and transceive information via communication resources or channels, consoles or operator stations, a resource allocator, a functions processor such as a computer aided dispatch computer (CAD), peripheral devices such as databases or modems, and a controlling entity. Operator stations provide access to the system for supervisors and dispatchers by allowing an operator to monitor the system and request specific functions. The CAD provides the dispatcher or supervisor with a computer interface and specialized software to carry out specific management and control functions.
Typically, the console and the CAD each communicate with the base stations via separate and distinct interfaces. In one system configuration, there is no interface between the console and the CAD. This system configuration is inefficient for the operator since it requires the operator to physically move from the console to the CAD when the operator desires to send a request that only the CAD can perform, such as sending a page; or physically move from the CAD to the console when the operator desires to send a request that only the console can perform, such as accessing a radio channel. This configuration also requires the operator to know multiple methods of sending requests, both via the CAD and via the console.
In another system configuration, an interface exists between the CAD and the console. In this configuration, the CAD contains intelligence to process all requests from the operator while the console only performs console services such as group dispatch, accessing a channel, etc. When the CAD receives a request from the operator, the CAD determines whether the CAD is to perform the request or whether a peripheral device is to perform the function. While this configuration only requires the operator to know one method of sending requests and does not require the operator to physically move back and forth between the console and the CAD, a backup mechanism is not provided to accommodate the system if the CAD becomes inoperable.
In system configurations comprising an interface between the CAD and the console, a mechanism for providing main/alternate routing may be implemented. In main/alternate routing, if a communication link fails between the CAD and a peripheral device, an alternate route is employed for communication. In this manner, the system continues to operate. However, if the communication link between the CAD and the console fails, main/alternate routing does not provide an alternate route for communication between the CAD and console. Thus, functions initiated through the CAD and intended for the console are not performed as requested.
Therefore, a need exists for a method that does not require the operator to know multiple procedures of sending requests, that does not require the operator to physically move back and forth between the CAD and the console, that provides a backup mechanism to keep the system operating if the CAD becomes inoperable, and that provides a mechanism to keep the system operating if the communication link between the CAD and the operator station fails.